Purchasing decisions on date palm fruits: A quantitative analysis of the Khalas cultivar

This study examines the attributes of date palm fruits that influence consumer purchasing decisions and measures the attributes’ relative importance weights for understanding consumption patterns relative to the cultivation areas. A case study was conducted for a selected date fruit, Khalas, which is cultivated in Saudi Arabia and ranked first in the world in exported dates. Our empirical investigation is based on utilizing a proposed quantitative analysis that integrated the entropy weighting method and binary logit models. With this survey design, 486 questionnaires were collected. Analysis results revealed a ranking list of preferred attributes, with size, mellowness, price, and color being the most valued. However, this ranking list fluctuates when different cultivated types of Khalas dates are available. The results also showed that consumption patterns may change in terms of preference index and shopping location. The paper concludes with a discussion of managerial implications, limitations, and future research directions.


Introduction
Since ancient times, the palm has been known as a tree characterized by many unique qualities. It is one of the most important means of food security for desert dwellers and is known as the tree of life in desert areas. Economically, dates are one of the most prominent products of the palm tree (Phoenix dactylifera L.), and they have great nutritional value because of the vital compounds they contain [1,2]. Date palm fruits contain a single seed enclosed by fibrous and parchment-like endocarp, fleshy mesocarp, and the fruit's skin (pericarp). Different regions produce different date fruits that vary in shape, size, and color. Accordingly, they can vary in their organoleptic, physical, and chemical characteristics [3,4]. In addition, it has become an important export commodity in a number of countries around the world, but especially in the Middle East and North Africa, with Saudi Arabia at the forefront [5]. Saudi Arabia is the third largest producer of date fruits in the global market [2,6].
In Saudi Arabia, special attention is paid to the palm and date fruits sector, as it is one of their most significant agricultural sectors, and the kingdom's exported dates achieved an increase of 7% in value and 17% in quantity during 2020 [7]. In 2021, the total value of exported dates amounted to 1.215 billion riyals for 113 countries around the world, and Saudi Arabia ranked first globally in the export of dates by value [8]. These statistics indicate the increasing price, production, and consumption of dates domestically and globally. Several date products have attractive market value in Saudi and international markets, e.g., Ajwa, Safawi, Sukkary, Khalas, and Sheshi [9]. One of the popular date varieties in Saudi Arabia is Khalas, which is a cultivar of the palm date that has brown skin and is widely grown in Saudi Arabia and the Arab Gulf region. Furthermore, the Khalas cultivar ranked first in terms of the number of palm trees in Saudi Arabia, with 7,903,51 trees (25%) out of 31,234,155 total palm trees. In 2019, Khalas palm trees produced 422,694.8 tons of dates, and 384,394.1 tons were sold [10]. Further, there is a diversity of Khalas date cultivation areas in Saudi Arabia, such as Qassim, Al-Ahsa, and Riyadh. Although the Khalas cultivar is originally from Al-Ahsa [11], it has been also cultivated in abundance in Qassim and Kharj, and its quality differs based on where it is grown. This fact has influenced consumer purchasing decisions and created more competition in the domestic market for Khalas dates.
In recent years, there has been a growing focus on increasing the productivity and quality of fruit trees and consumer awareness of the demand for fresh fruits. This is characterized by external (formal) and internal (eating) quality, which gives the fruit the quality and characteristics desired by the consumer [12]. In terms of nutritional value, dates have exhibited several health benefits, as they have high amounts of phytochemicals [13]. Moreover, the external attributes of dates (e.g., size and color) may improve aspects of consumer preferences [14], and the origin of different dates may lead to different attributes (e.g., price and size), which in turn affect consumer preferences [15].
To the best of our knowledge, empirical analysis of consumer preferences for purchasing Khalas dates with certain attributes based on place of origin is scarce. Thus, this paper seeks to reveal how a preference for certain Khalas dates based on their place of origin can influence consumer purchasing decisions regarding other available Khalas dates. Since Al-Ahsa, Qassim, and Kharj are the three major areas that cultivate and produce dates, this research focuses on these three areas in Saudi Arabia as a case study. As a result of this research, farmers and workers in this major sector can achieve consumer satisfaction, which in turn will achieve maximum economic benefits and reduce waste. Based on these considerations, this study intended to achieve the following aims: (1) explore the impact of Khalas date attributes on consumer preferences for purchasing decisions is the first aim; (2) rank Khalas date attributes from the least to most important according to the cultivation/production areas is the second aim; and (3) create a quantitative preference index to measure the impact of preference on consumer purchasing decisions is the third aim. To address these research goals, this study applied an integrated quantitative analysis based on the entropy weighting method and binary logit models.
This research contributes to the literature by providing insights into consumer preferences that indicate potential areas of marketing and producer focus for date palm fruit markets. This is one of the first empirical applications in marketing that focuses specifically on Khalas date attributes concurrently with cultivation areas by conducting the proposed integrated quantitative analysis. Researchers, date producers, traders, and exporters may find this research to be a suitable framework to understand the field of date palm fruit marketing. Moreover, this study will provide a scientific framework to aid date producers and traders in improving the cultivation process and understanding the attributes that affect consumption preferences. Consequently, this can enhance the ability to compete in the market in the presence of other products that have different attributes.

Prior research and research gap
Consumers are now being considered as the major driving force in agribusiness industry development. In recent years, a greater emphasis was being placed on studying and analyzing consumers' behavior in purchasing decision for agri-food products. In the literature, efforts to understand consumer attitudes and the relative importance of various attributes in purchasing fruits products have been widely explored. The prior framework of consumer behavior proposes that fruits products choices are the result of considering external (formal) and internal (eating) factors [16]. Regarding date palm fruits, a stream of literature discuses that the external attributes of dates (e.g., size, color, texture, and price) may improve aspects of consumer preferences [14][15][16]. In addition, some authors have claimed that nutritional value characteristics (e.g. texture, and health benefits) might affect consumer purchasing decision [13,16]. A further stream of literature has investigated the consumer preferences and behavior patterns in purchasing food products that are influenced by socio-demographic characteristics of consumers. [17] showed that Norwegian consumers' willingness to pay for African dried fruit (bananas, pineapples, and man-goes) is influenced by gender and education. [18] suggested that consumers income do play a role in shaping the demand for orange fruits in Oman. [19] found that there are differences in the purchasing and consumption behavior of Greek consumers across generations for organic food products. [20] showed that the age of Italian consumers is a significant driver of willingness to accept purchase olives leaves. [21] reveled those socio-economic characteristics of consumers, the age, education, and income have positive impacts on Willingness to Pay of dairy products in China. However, there are no studies to the best of our knowledge that considering consumer preferences for purchasing fruits products, specially Khalas dates, with certain attributes (color, price, fillings, mellowness, and size) integrated with based on cultivation areas is limited.
In terms of methodological approaches, consumer choices of fruit products are modelled using different models in the previous research such as contingent valuation, the experimental approach and logit models [21][22][23][24]. The most recent and suitable model was the logit models for estimating for the various preference index of fruit products for studying consumer purchasing choices [16,21,25,26]. However, the previous studies in date industry were rare to propose a weighting method for measuring the importance weights of fruits products attributes and then offering a ranked list of attributes. Thus, there is need to develop an integrated methodology for estimating and analyzing consumer choices of fruit products and at the same time measuring the importance weights of fruit products' attributes. As far as we know, this study is the first study that propose an integrated quantitative analysis based on the entropy weighting method and binary logit models.

Overview of the Saudi Khalas date market
With regard to the quality standards for Khalas dates, it has been found that the Ministry of Environment, Water, and Agriculture has set standard standards for date quality to help facilitate domestic and international trade, promote high-quality production, improve the economic return of producers and exporters, and protect consumer interests. The agricultural quality standards [27] for dates are used by producers, traders, importers, and exporters.
Regarding the diversity of Khalas date cultivation areas in Saudi Arabia, Riyadh came in first place for the number of palm trees of the Khalas cultivar with 3,200,668 trees, comprising 40% of the total number of Khalas date palm trees in the kingdom; the eastern region came in second place with a total of 2,640,307 palm trees of the Khalas cultivar, or 33% of the country's total; and the area of Qassim came in third place, as it contained 1,510,776 Khalas date palm trees, which is 19% of the kingdom's total [10]. Khalas is also one of the most highly regarded dates in the eastern region. It is considered an excellent variety and represents 15-20% of Al-Ahsa palms, and it is believed to be native to the oasis of Al-Hofuf in the land of Al-Ahsa [11]. It is harvested and consumed unripe dates and ripped dates. The problem of harvesting small sized dates, especially in the Qatif region, is one of the factors limiting dates marketing [17]. This issue reduces consumer's demand and eventually the economic return of farmers.

Sample and location
The data required for this research was primary data collected through a designed survey. The required sample size was determined using the Stephen Thompson equation [28].
Where n is the minimum required sample size, N is the population size where the Khalas date type i is cultivated, i.e. the combined population in Riyadh region, Al-Qassim, and eastern region (N = 15297768) [29], P is a probability value that takes a value from 0 to 1 (we set it equal to 0. 5), d is the margin of error (equal to 0.05), and z is a standardized value equal to 1.96. The results of the Thompson equation revealed that the minimum sample size should be 384 respondents. Opportunely, the number of collected observations reached a total of 486 participants. The samples were taken proportionally from date consumers in central and eastern provinces of Saudi Arabia. Enumerators were employed to distribute the survey questionnaires. Ethical approval for this study was given by the Ethical Committee at King Faisal University, and the approval reference number is KFU-REC-2022-AUG-ETHICS93. Researchers informed all participants of the reason for the research being conducted, and this was included in the introduction of the designed survey. No verbal or written consent was requested from participants because the survey does not include questions related to participants' identity and the data were collected and analyzed anonymously.

Questionnaire design
In this research questionnaire, all the variables (e.g., Khalas date types and attributes) and items used were designed based on date palm research, general knowledge of local consumers, and informal discussions with experts. The questionnaire was composed of two sections. Section one included ten questions covering the demographic background of the respondents and other variables regarding attitudes when purchasing dates. Thus, section one considered several elements: age, gender, marital status, educational level, household size, nationality, monthly income, date shopping locations, date consumption, and preference index. Section two of the questionnaire comprised five questions asking the respondents to rank their level of purchase intention for different types of date fruits based on their area of cultivation with respect to various attributes. In this research, the three most cultivated types of Khalas date fruits [10] offered as alternatives in the ranking procedure were Al-Ahsa, Al-Kharj, and Al-Qassim Khalas dates. In addition, five date selection attributes were reflected in this study: color, price, fillings, mellowness, and size. The ranking questions were measured using fivepoint linguistic variables, from very high important (VH) to very low important (VLI). Table 1 shows the linguistic variable measurements and their equivalent numerical scales [30].

Data analysis: An integrated quantitative analysis
This research consisted of an integrated quantitative analysis based on the entropy weighting method and binary logit models, which were proposed to achieve the aims of this study. The first and second aims were accomplished by applying the entropy weighting method, and binary logit models were employed to accomplish the first and third aim. Weighting methods are commonly used for studying the preferences of online consumers by measuring the importance weights of attributes and then offering a ranked list of attributes [31]. In the literature, there are several weighting methods. SWING SMARTS, SMARTER, direct rating, Criteria Importance Through Inter-criteria Correlation, and the entropy weighting method were recent methods used in survey-based preference elicitation [32,33]. In this study, the entropy weighting method was adopted, which has been introduced to information theory to measure the amount of useful information in data provided by consumers. It focuses on the discrimination among data to determine the weighing of different attributes [34]. The calculation process for the entropy weighting method can be expressed as follows [31,33]: With respect to A i , i = 1,2,3 denotes the number of the alternatives (here alternatives are three different kinds of Khalas: Al-Ahsa, Al-Kharj, and Al-Qassim dates). Answers provided by the respondents (date consumers) in the online survey were extracted from the survey database and saved in the data matrix X, consisting of the values x nm as T = [t ij ] M×N , j = 1,. . .N denotes the number of the attribute B n (here N = 5, indicates five date selection attributes: color, price, fillings, mellowness, and size), and i = 1,. . .M denotes the number of the respondents. The weighting vector W represents the relative importance weights of B j selection attributes and can be expressed as follows: W = {w 1 ,w 2 ,. . ..w N }. After elicitation of consumer preferences, the decision matrix T will normalize as follows: Then, an entropy e j will be calculated using the following equation: Where ln 1 M À � À � À 1 is the entropy constant, which assures 0 � e j � 1. Afterward, the degree of divergence d j of the inherent information of each attribute B j will be defined as: Lastly, the relative importance weight w j for each attribute B j will be obtained using: In order to know how consumer preference for a certain type of Khalas date may influence their purchasing decisions for other types of Khalas dates, we will use a binary logit models specified below:  Where L A i is the logit representing consumer purchasing decisions of Khalas type is the log of odds ratio, β 0 is the intercept, β 1 . . . β k are parameters to be estimated, and X 1 . . . X k are vectors of independent variables. We will run the logit model three times, where the dependent variable will be consumer purchasing decisions with Khalas type A i . The explanatory variables will be the consumer preference index for type A i of Khalas dates and other socio-economics factors that may influence consumer purchasing decisions. The preference indices will be constructed using a principal component analysis (PCA).

General analysis
The sampling process achieved a sample size of 486 useable responses. Statistical analyses for the data collected from the sample were conducted using Microsoft Excel and R software. Table 2 illustrates the respondent profiles and summary statistics of the key variables. Descriptive statistics for the sample (Table 2) reveal a slight majority of male respondents (55%), with fewer female respondents (45%). Most respondents (63%) hold a university degree. Around 38% of them purchase Khalas dates from date markets, and about a quarter of them (25.10%) purchase Khalas dates directly from the farm owner. Also, we test the null hypothesis that the mean attributes (color, price, fillings, mellowness, and size) are equal for the three cultivation regions (Al-Ahsa, Al-Kharj, amd Alqassim). Thus, we conducted a one-way ANOVA test and Kruskal-Wallis test because the results of Shapiro-Wilk normality test (available upon request) showed that normality assumption did not hold. Nonetheless, the results of both ANOVA and Kruskal-Wallis test rejected the null hypotheses as stated in Table 3. The results show that consumers assign different level of the mean

4.2.Attribute importance weighting and ranking
In this research, the entropy weighting method was used to measure the relative weights for selection attributes of Khalas dates and then rank them. Two scenarios were examined for weighting and ranking the attributes. The first related to different cultivated types of Khalas dates (alternatives), since the attributes of Khalas dates vary from one cultivated region to another [35]. The second scenario was with respect to Khalas date fruits in general. Weighting and ranking of the attributes for both scenarios are illustrated in Table 4.
Regarding the first scenario, ranking Khalas date attributes from the least to the most important according to the cultivation areas is illustrated in Table 4, and visual comparisons are shown in Fig 2. The least important attribute is fillings, while the most important attributes are mellowness, price, and size for Al-Ahsa, Al-Kharj, and Al-Qassim Khalas dates, respectively. From this analysis, it is clear that the weights and ranks are inconstant in terms of four attributes: color, price, mellowness, and size. Accordingly, consumer purchasing decisions are differentiated by these four attributes when different cultivars of Khalas dates are available in the market, while the fillings attribute does not influence consumer purchasing decisions.
Regarding the second scenario, weighting and ranking of the attributes is shown in the last two rows in Table 4, and visual illustration is provided in Fig 3. The displayed results express that overall, the ranking of importance attributes that affect consumer preferences is in order of size, mellowness, price, and color. Like the first scenario's results, the fillings are not an important attribute for consumers to consider when deciding to purchase Khalas dates.

4.3.Consumer preference index
The PCA was applied to construct a single index by utilizing Khalas date attributes B j : color, price, fillings, mellowness, and size. The results of the PCA are reported in Table 5.
Based on the results of the PCA, we selected the first components for the three Khalas dates varities because their eigenvalues are greater than one. Thus, we construct the preference indices for the Khalas dates variaties by expressing the components as a linear combination of the observed variables as below: Al À Ahsa Preference Index Factors influencing consumer purchasing decisions for Khalas dates by area of cultivation were estimated with binary logit models. The results of the three models representing each area of cultivation (Al-Ahsa, Al-Kharj, and Al-Qassim) are shown in Table 6. As expected, the results show that consumer preferences for a certain type of date increases the odds of consuming that particular date, which is clearly observed through the highly significant own-preference coefficients for Al-Ahsa, Al-Kharj, and Al-Qassim Khalas dates, respectively. Conversely, a one-unit increase in the consumer preference score for Al-Kharj Khalas dates indicates a decrease in the odds of consuming Al-Ahsa Khalas dates by 17%. Furthermore, a one-unit increase in the consumer preference score for the Al-Ahsa and Al-Qassim dates indicates a decrease in the odds of consuming Al-Kharj Khalas dates by 28% and 33%, respectively. The same pattern is observed when it comes to the consumer decision to consume Al-Qassim Khalas dates: A one-unit increase in the consumer preference score for Al-Ahsa and Al-Kharj Khalas dates shows a decrease in the odds of consuming Al-Qassim Khalas dates

PLOS ONE
Date fruits Consumer preferences by 19.5% and 17%, respectively. Overall, the results indicate that as the own-preference coefficient score for type A i dates increases by one point, the odds of consuming the same type also increases. Conversely, the cross-preference coefficients indicate that a one-unit increase in the preference score for type A i dates decreases the odds of consuming other types of dates.
Consumers who buy their dates directly from farm owners are less likely, on average, to consume Al-Kharj and Al-Qassim dates. Consumers who rely on their own farm as their main source of Khalas dates also have lower odds of consuming Al-Kharj and Al-Qassim Khalas dates, while they have higher odds of consuming Al-Ahsa Khalas dates. This can be attributed to the fact that the prices of Al-Kharj and Al-Qassim Khalas dates are higher than Al-Ahsa Khalas dates, so it is more profitable to sell Al-Kharj and Al-Qassim Khalas dates than Al-Ahsa Khalas dates. As results, the consumption decisions of consumers affected by the consumer's preferred shopping location when they intend to purchase the Khalas dates.
Furthermore, as the household size increases the odds of purchasing Al-Qassim Khalas dates decreases. Conversely, older consumers and holders of associate degrees are less likely to consume Al-Qassim Khalas dates. In addition, consumers whose level of education is high school or less have higher odds of purchasing Al-Kharj Khalas dates while consumer with graduate degrees have lower odds of purchasing Al-Ahsa Khalas dates. The odds ratios in Table 6 also reveal that income does not influence the odds of consuming all the varieties of Khalas dates under investigation. This is attributed to the fact that dates are necessary commodity in Saudi Arabia and increases in income does not significantly increase dates consumption.
In order to conduct robustness check on the estimated results, we re-estimate the model with uniform samples, i.e. we created subsamples from the original data for the three dates varieties with equal number of consumers and non-consumers (111 consuming participants and 78 non-consuming participants). The results of the uniform samples in Table 6 shows that the significance level has changed for some of the preference variables. However, almost all the signs of the preference coefficients remained the same, which confirms that our results are robust.

Discussion and conclusion
This research explored the expressed preferences of a sample of 486 consumers in Saudi Arabia regarding purchasing decisions on a specific type of palm date product known as Khalas dates. In general, when consuming Khalas fruits from different areas of origin and cultivation, consumers were mainly influenced by attributes such as color, price, fillings, mellowness, and size. The proposed quantitative analysis, which integrated the entropy weighting method and binary logit models, was applied to study the purchasing decisions on Khalas date palm fruits. Several of the findings are managerially and theoretically relevant. First, producers and traders should understand their targeted consumers since their preferences may change based on the varies date attributes. Second, the size, mellowness, price, and color attributes of dates, respectively, might be considered the preferred attributes of consumers. Therefore, producers that are active in the Khalas date industry may adapt their products to meet the preferences of their consumers. Some attributes of the product, especially sensory attributes (i.e., size, mellowness, and color), can be improved. As stated in the literature, there are new techniques to significantly improve the sensory attributes of cultivars. For instance, solar drying methods [36], automated irrigation systems [37], and the use of mycorrhizal fungi [38]. In terms of price attributes, financial and economic studies must be conducted by traders and exporters to understand the Khalas date market. Third, the results from the binary logistic regression models reveal that there is a direct positive relationship between consumer preference for a specific type of Khalas date based on its place of origin and the odds of consuming that specific type. However, this correlation decreases when there are two types of Khalas dates. Furthermore, consumer consumption decisions regarding Khalas dates is affected by the consumer's preferred shopping location. Thus, marketing studies should be conducted frequently and include consumer preference indexes, income, shopping location, etc., to understanding purchasing decision patterns correctly. Generally, all previous results have proved the importance of running scientific marketing studies to explore the strengths that need to be supported and weaknesses that need to be addressed regarding purchasing decisions on date palm fruits. Finally, although our study focused on Khalas date fruits, the proposed quantitative analysis is likely to be relevant in other consumption contexts.
There are some limitations that can be improved by future research. First, the questionnaire was applied to a relatively small geographical area (consumers from central and eastern provinces of Saudi Arabia). In addition, this research only reflects five attributes of dates. Thus, researchers should incorporate more attributes and expand future research with a larger sample size. Second, the study only attempted to explore the preferences of consumers regarding purchasing decisions on date palm fruits within certain environments and did not address the uncertainty and lack of precision associated with consumer judgment and preferences. In future research, it would be interesting to utilize fuzzy set theory to study this topic with the inclusion of consumer preferences and decisions within uncertain environments. Third and most importantly, the collected consumption responses regarding Khalas dates varieties were heterogenous. We recommend for future research to consider two potential solutions in order to address potential consumption heterogeneity. The first solution is to conduct discrete choice experiment and use models that take into account consumers heterogeneity such as mixed logit model and latent class models [39]. The second recommended solution is to adjust the imbalance in consumption patterns using resampling methods such as under-sampling (decreasing majority class consumption observations to be equal to minority consumption class) or oversampling (increasing minority class consumption observations to reach to the majority class consumption) [40,41]. Finally, while these limitations hinder and make the generalizability of the findings questionable, there are promising opportunities for strengthened results with further studies.
Supporting information S1 File. The dataset in this file was collected from respondents residing in Eastern and Central region in Saudi Arabia. (XLSX)